Polymer composition comprising a polymer having a gradient polymeric morphology

ABSTRACT

An aqueous composition comprising components: (A) 50 to 99 wt. % of a vinyl polymer(s) having a gradient polymeric morphology; and (B) 1 to 50 wt. % of at least one polymer not having a gradient polymeric morphology, wherein components (A) and (B) add up to 100%.

[0001] The present invention relates to certain aqueous compositionscomprising 50 to 99 wt. % of vinyl polymers having a gradient polymericmorphology and to their use in coating applications.

[0002] A vinyl polymer having a gradient polymeric morphology is a vinylpolymer having a continually changing monomeric compositional content.The preparation of vinyl polymers having a gradient morphology is wellknown in the art. U.S. Pat. No. 3,804,881 discloses a process forpreparing vinyl polymers having a gradient polymeric morphology wherethe process comprises polymerising at least one primary polymerisablemonomer feed varying in compositional content by continuously adding atleast one different secondary polymerisable monomer feed. Thisdisclosure describes a wide variety of configurations that can be usedto prepare polymers having a gradient polymeric morphology. U.S. Pat.No. 4,039,500 also discloses a process for controlling particlemorphology and the molecular weight distribution of vinyl polymers. U.S.Pat. No. 6,140,431 discloses a further process for the preparation ofcontinuously variable composition copolymers, in particular for use inlubricating oil additives.

[0003] WO 97/12921 discloses a seed polymerised latex having a gradientpolymeric morphology and a process for making such a process. U.S. Pat.No. 4,111,876 discloses a blend of up to 15 wt. % of a polymer derivedfrom styrene, acrylonitrile and acrylate ester monomers having agradient polymeric morphology and the remainder comprising a poly(vinylchloride) resin, to provide greater impact resistance, however U.S. Pat.No. 4,111,876 also teaches that use of more than 15 wt. % of the polymerhaving a gradient polymeric morphology negates any improvement.

[0004] There is an increasing requirement to significantly reduce oreliminate volatile organic contents (VOC's) in aqueous polymercompositions due to the environmental toxicity and flammability problemsassociated with VOC's. However up to now the use of a certain amount oforganic coalescing solvent in the final composition has been found toaid film-formation on coating of the composition onto the substrate. Ithas also been found difficult to achieve a composition containing no orvery little coalescing solvent but still having a good balance ofproperties conventionally required in most coating applications such ashigh hardness and a low minimum film forming temperature (MFFT).

[0005] We have now invented an aqueous composition providing anadvantageous combination of MFFT, hardness and elasticity.

[0006] According to the present invention there is provided an aqueouscomposition comprising in admixture components:

[0007] (A) 50 to 99 wt. % of a vinyl polymer(s) having a gradientpolymeric morphology; and

[0008] (B) 1 to 50 wt. % of at least one polymer not having a gradientpolymeric morphology;

[0009] wherein components (A) and (B) add up to 100%.

[0010] Preferably the aqueous composition of the invention comprises 60to 95 wt. % of component (A) and 5 to 40 wt. % of component (B), morepreferably 70 to 90 wt. % of component (A) and 10 to 30 wt. % ofcomponent (B), and most preferably 75 to 90 wt. % of component (A) and10 to 25 wt. % of component (B).

[0011] Vinyl polymers are derived from free radically polymerisableolefinically unsaturated monomers (herein defined as vinyl monomers) andcan contain polymerised units of a wide range of such vinyl monomers,especially those commonly used to make binders for the coatingsindustry.

[0012] Component A, the vinyl polymer(s) having a gradient morphologymay be prepared by any of the process variations described in U.S. Pat.No. 3,804,881 (incorporated herein by reference). A gradient polymericmorphology may be obtained by the polymerisation of at least a firstmonomer feed and a different second monomer feed.

[0013] A typical process for preparing a vinyl polymer(s) having agradient polymeric morphology comprises introducing a first monomer feedto a reactor, where the first monomer feed continually varies in itscomposition due to the addition of a different second monomer feed tothe first monomer feed and polymerising the monomers introduced into thereactor.

[0014] The addition of the second monomer feed to the first monomer feedmay be in parallel to the introduction of the first monomer feed to thereactor (i.e. both feeds start and end at the same time). Alternativelythe start of the first monomer feed to the reactor may precede the startof the addition of the second monomer feed to the first monomer feed forexample when preparing a vinyl polymer using a seeded polymerisationprocess, or both monomer feeds may be started simultaneously but thetime taken for the addition of the second monomer feed to the firstmonomer feed may exceed the time taken for the introduction of the firstmonomer feed to the reactor. The seed may comprise up to 10 wt. % of thefirst monomer feed.

[0015] A gradient polymeric morphology may also be obtainable from aprocess comprising simultaneously introducing a first monomer feed and adifferent second monomer feed into a reactor where the rate ofintroduction of the first monomer feed varies with respect to the rateof introduction of the second monomer feed and polymerising the monomersintroduced into the reactor.

[0016] The at least two monomer feeds used to prepare the vinylpolymer(s) having a gradient polymeric morphology usually differ incomposition. The difference between the at least two monomer feeds maybe any, including for example a difference in glass transitiontemperature (Tg), monomer functionality (for example the use ofcrosslinking, acid functional or adhesion promoting monomers),hydrophilicity, refractive index, molecular weight or simply a variationin the concentration of the respective monomers in each monomer feed. Ifthere is a Tg difference between the at least two monomer feeds, theresulting vinyl polymer(s) having a gradient polymeric morphology maylack a clearly definable measured glass transition temperature (Tg)because of the continually changing monomeric compositional content.

[0017] Examples of vinyl monomers which may be used to form vinylpolymer(s) having a gradient polymeric morphology include but are notlimited to 1,3-butadiene, isoprene, styrene, a-methyl styrene, divinylbenzene, acrylonitrile, methacrylonitrile, vinyl halides such as vinylchloride, vinylidene halides such as vinylidene chloride, vinyl esterssuch as vinyl acetate, vinyl propionate, vinyl laurate, and vinyl estersof versatic acid such as VeoVa 9 and VeoVa 10 (VeoVa is a trademark ofShell), heterocyclic vinyl compounds, alkyl esters of mono-olefinicallyunsaturated dicarboxylic acids (such as di-n-butyl maleate anddi-n-butyl fumarate) and, in particular, esters of acrylic acid andmethacrylic acid of formula

CH₂═CR¹—COOR²

[0018] wherein R¹ is H or methyl and R² is optionally substituted alkylor cycloalkyl of 1 to 20 carbon atoms (more preferably 1 to 8 carbonatoms) examples of which are methyl acrylate, methyl methacrylate, ethylacrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate,2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, isopropyl acrylate,isopropyl -methacrylate, n-propyl acrylate, n-propyl methacrylate,trifluoroethyl(meth)acrylate, dimethyl aminoethyl methacrylate andhydroxyalkyl (meth)acrylates such as hydroxyethyl acrylate, hydroxyethylmethacrylate, 2-hydroxypropyl methacrylate, 2-hydroxypropylacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate and theirmodified analogues like Tone M-100 (Tone is a trademark of Union CarbideCorporation).

[0019] Olefinically unsaturated monocarboxylic acids, sulphonic acidssuch as 2-acrylamido-2-methyl-propane sulphonate (AMPS) and/ordicarboxylic acids, such as acrylic acid, methacrylic acid, β-carboxyethyl acrylate, fumaric acid and itaconic acid, and monomers such asN-methylol(meth)acrylamide, methoxy polyethyleneoxide(meth)acrylate and(meth)acrylamide may also be used.

[0020] The vinyl monomer may optionally contain functional groups tocontribute to the crosslinking of the vinyl polymer(s) having a gradientpolymeric morphology in the coating. Examples of such groups includemaleic, epoxy, fumaric, acetoacetoxy such as acetoacetoxyethylmethacrylate, β-diketone, unsaturated fatty acid, acryloyl, methacrylol,styrenic, (meth)allyl groups, mercapto groups, keto or aldehyde groups(such as methylvinylketone, diacetoneacrylamide and (meth)acroleine).

[0021] Particularly preferred are vinyl polymer(s) having a gradientpolymer morphology made from a monomer system comprising at least 40 wt.% of one or more monomers of the formula CH₂═CR¹COOR² as defined above.Such preferred vinyl polymer(s) are defined herein as acrylicpolymer(s). More preferably, the monomer system contains at least 50 wt.% of such monomers, and particularly at least 60 wt. %. The othermonomers in such acrylic polymer(s) (if used) may include one or more ofthe other vinyl monomers mentioned above, and/or may include onesdifferent to such other monomers. Particularly preferred monomersinclude butyl acrylate (all isomers), butyl methacrylate (all isomers),methyl methacrylate, ethyl hexyl methacrylate, esters of (meth)acrylicacid, acrylonitrile, vinyl acetate and styrene.

[0022] In a preferred embodiment the vinyl polymer(s) having a gradientpolymeric morphology is prepared from at least a first monomer feed anda different second monomer feed.

[0023] Preferably either the first monomer feed and/or the secondmonomer feed comprises composition (a):

[0024] i) 10 to 90 wt. %, more preferably 20 to 80 wt. % and mostpreferably 25 to 70 wt. % of CH₂═CR¹—COOR² wherein R¹ is H or methyl andR² is optionally substituted alkyl or cycloalkyl of 1 to 20 carbonatoms;

[0025] ii) 0 to 40 wt. %, more preferably 0 to 30 wt. % and mostpreferably 0 to 25 wt. % of styrene;

[0026] iii) 0 to 15 wt. %, more preferably 0 to 10 wt. % and mostpreferably 0 to 6 wt. % of acid functional vinyl monomer(s);

[0027] iv) 0 to 10 wt. %, more preferably 0 to 7 wt. % and mostpreferably 0 to 5 wt. % of crosslinking functional vinyl monomer(s);

[0028] v) 0 to 5 wt. %, more preferably 0 to 4 wt. % and most preferably0 to 3 wt. % of chain transfer agent(s);

[0029] vi) 0 to 20 wt. %, more preferably 0 to 15 wt. % and mostpreferably 0 to 10 wt. % of vinyl monomer(s) not in i) to v);

[0030] where i)+ii)+iii)+iv)+v)+vi) add up to 100%; and

[0031] wherein said second monomer feed is different from said firstmonomer feed.

[0032] Preferably either the first monomer feed and/or the secondmonomer feed comprises composition (b):

[0033] i) 10 to 90 wt%, more preferably 20 to 80 wt. % and mostpreferably 25 to 70 wt. % of CH₂═CR¹—COOR² wherein R¹ is H or methyl andR² is optionally substituted alkyl or cycloalkyl of 1 to 20 carbonatoms;

[0034] ii) 0 to 40 wt. %, more preferably 0 to 30 wt. % and mostpreferably 0 to 25 wt. % of styrene;

[0035] iii) 2 to 20 wt. %, more preferably 2 to 15 wt. % and mostpreferably 2 to 10 wt. % of acid functional monomer(s);

[0036] iv) 0 to 30 wt. %, more preferably 0 to 20 wt. % and mostpreferably 0 to 15 wt. % of crosslinking functional monomer(s);

[0037] v) 0 to 10 wt. %, more preferably 0 to 5 wt. % and mostpreferably 0 to 3 wt. % of chain transfer agent(s);

[0038] vi) 0 to 20 wt. %, more preferably 0 to 15 wt. % and mostpreferably 0 to 10 wt. % of vinyl monomer(s) not in i) to v);

[0039] where i)+ii)+iii)+iv)+v)+vi) add up to 100%; and

[0040] wherein said second monomer feed is different from said firstmonomer feed.

[0041] Most preferably when the first monomer feed comprises composition(a), the different second monomer feed comprises composition (b) andwhen the first monomer feed comprises composition (b) the differentsecond monomer feed comprises composition (a).

[0042] Preferably the weight ratio of the first monomer feed to thesecond different monomer feed is in the range of from 70:30 to 30:70.

[0043] The vinyl polymer(s) having a gradient polymeric morphology maybe prepared by any known technique including those discussed above andmay include directly synthesising the vinyl polymer(s) in water (forexample by emulsion polymerisation, micro-suspension polymerisation ormini emulsion polymerisation). Methods for preparing aqueous vinylpolymer(s) are reviewed in the Journal of Coating Technology, volume 66,number 839, pages 89 to 105 (1995) and these methods are included hereinby reference.

[0044] Component (B), the at least one polymer not having a gradientpolymeric morphology may be any polymer known in the art including butnot limited to vinyl polymers such as polyvinyl acetate, polybutadiene,(meth)acrylic polymers prepared by chain transfer polymerisation,acrylic polymers containing styrene, acrylonitrile,2-(dimethylamino)ethyl methacrylate (DMAEMA) and or methacrylamidemonomers; polyvinyl(di)chloride, polymers containing VEVOVA monomers(available from Resolution); fluorinated vinyl polymers and acrylicpolymers; vinyl chloride/acrylonitrile resins; hybrids such aspolyurethane acrylic hybrids, alkyd acrylic hybrids and polyesteracrylic hybrids; hyperbranched polymers such as dendrimers; oils such assaturated and unsaturated oils; hollow particles (available under thename Ropaque); polymers disclosed in EP 758364 and EP 758347incorporated herein by reference; waxes such as paraffin; melamineresins; phenolic resins; Lumiflon resins (available from Avecia Ltd);silicone resins; polycarbonate resins; polyamide resins; polyketoneresins; polyether resins; Haloflex resins (available from Avecia Ltd);hydroxy functional resins as a used in two pack iscocyanateapplications; polyurethanes; autoxidisably crosslinkable polymers and UVcurable polymers. Component (B) is preferably in the form of an aqueousdispersion. By keeping the solvent low the amount of volatile organiccoalescents are reduced. Preferably component (B) is selected from thegroup comprising:

[0045] (i) vinyl polymer(s) having a Tg≧50° C. and a particle size≧150nm;

[0046] (ii) water-dissipatable polyurethane(s);

[0047] (iii) UV curable polymer(s); and

[0048] (iv) autoxidisably crosslinkable polymer(s);

[0049] Component (B) if a vinyl polymer, may be prepared by a seededpolymerisation process.

[0050] If component (B) is a vinyl polymer selected from (i) thencomponent (B)(i) may be formed from vinyl monomers as described hereinfor the preparation of the vinyl polymer(s) having a gradient polymericmorphology. Component (B)(i) may be a multistage vinyl polymer orpreferably may be a single stage vinyl polymer.

[0051] Preferably component (B)(i) has a theoretical Tg≧60° C., morepreferably≧70° C. and most preferably≧90° C. Preferably component (B)(i)has a particle size≦140 nm, more preferably≦100 nm and mostpreferably≦60 nm. Preferably component (B)(i) has a weight averagemolecular weight≧100,000 Daltons. Preferably component (B)(i) has anacid value from 0 to 50 mg KOH/g.

[0052] Methods for preparing component (B)(ii) are known in the art andare described in for example the Polyurethane Handbook 2^(nd) Edition, aCarl Hanser publication, 1994, by G. Oertel; and these methods areincluded herein by reference. The polyurethane polymer(s) may beprepared in a conventional manner by reacting an organicpolyisocyanate(s) with a compound(s) carrying isocyanate-reactive groups(also known as isocyanate-reactive compounds) by methods well known inthe prior art. Isocyanate-reactive groups include —OH, —SH, —NH—, and—NH₂.

[0053] Suitable polyisocyanates include aliphatic, cycloaliphatic,araliphatic and/or aromatic polyisocyanates. Examples of suitablepolyisocyanates include ethylene diisocyanate, 1,6-hexamethylenediisocyanate, isophorone diisocyanate, cyclohexane-1, 4-diisocyanate,4,4′-dicyclohexylmethane diisocyanate, p-xylylene diisocyanate,α,α′-tetramethylxylene diisocyanate, 1,4-phenylene diisocyanate,2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4′-diphenylmethanediisocyanate, polymethylene polyphenyl polyisocyanates,2,4′-diphenylmethane diisocyanate, 3(4)-isocyanatomethyl-1-methylcyclohexyl isocyanate and 1,5- naphthylene diisocyanate. Mixtures ofpolyisocyanates can be used and also polyisocyanates which have beenmodified by the introduction of urethane, allophanate, urea, biuret,carbodiimide, uretonimine, urethdione or isocyanurate residues.

[0054] Suitable isocyanate-reactive compounds include organic polyol(s)optionally bearing crosslinker groups or hydrophilic water-dispersinggroups.

[0055] The organic polyols include diols and triols and mixtures thereofbut higher functionality polyols may be used, for example as minorcomponents in admixture with diols. The polyols may be members of any ofthe chemical classes of polyols used or proposed to be used inpolyurethane formulations. In particular the polyols may be polyesters,polyesteramides, polyethers, polythioethers, polycarbonates,polyacetals, polyolefins or polysiloxanes. Preferred polyol molecularweights are from 250 to 6000, more preferably from 500 to 3000. Lowmolecular weight organic compounds containing at least one (preferablyat least two) isocyanate-reactive groups and having a weight averagemolecular weight up to 500, preferably in the range of 40 to 250 canalso be used. Examples include ethyleneglycol, neopentyl glycol,1-propanol, and 1,4-cyclohexyldimethanol.

[0056] Isocyanate-reactive organic compound(s) bearing crosslinkergroups include isocyanate-reactive organic compounds bearing fatty acidgroups which may be obtained by using techniques known in the art, e.g.from the reaction of a suitable fatty acid with a hydroxyl donor(preferably an alcohol or polyol) or amine donor to provide a compoundbearing fatty acid groups).

[0057] Isocyanate-reactive compound(s) bearing a non-ionic and/or ionichydrophilic water-dispersing group(s) (or group which may besubsequently easily converted to such a water-dispersing group, e.g. byneutralisation—such a group still being termed a water-dispersing groupfor the purposes of this invention) may be used as a reactant in thepreparation of the polyurethane polymer. Examples of such compoundsinclude carboxyl group containing diols and triols, for exampledihydroxy alkanoic acids such as 2,2-dimethylolpropionic acid or2,2-dimethylolbutanoic acid. Examples of preferred compounds bearingnon-ionic hydrophilic water-dispersing groups include methoxypolyethylene glycol (MPEG) with number average molecular weights of forexample 350, 550, 750, 1000 and 2000, as described in EP 0317258.

[0058] When an polyurethane polymer is prepared, it is conventionallyformed by reacting a a stoichiometric excess of the organicpolyisocyanate(s) with the isocyanate-reactive compound(s) undersubstantially anhydrous conditions at a temperature between about 30° C.and about 130° C. until reaction between the isocyanate groups and theisocyanate-reactive groups is substantially complete; the ratio ofisocyanate groups to isocyanate-reactive groups preferably being of fromabout 1:4 to about 4:1, more preferably of from about 1:2 to 2:1.

[0059] If desired, catalysts such as dibutyltin dilaurate and stannousoctoate, zirconium or titanium based catalysts may be used to assist thepolyurethane polymer(s) formation. An organic solvent may optionally beadded to control the viscosity. Examples of solvents includewater-miscible solvents such as N-methylpyrrolidone, dimethyl acetamide,glycol ethers such as butyldiglycol, methyl ethyl ketone and alkylethers of glycol acetates or mixtures thereof. Preferably no organicsolvents are added.

[0060] The polyurethane polymer(s) may be dispersed in water usingtechniques well known in the art. Preferably, the polyurethanepolymer(s) is added to the water with agitation or, alternatively, watermay be stirred into the polyurethane polymer(s).

[0061] Alternatively if an isocyanate-terminated polyurethane prepolymeris prepared and dispersed in an aqueous medium the prepolymer may bechain extended with active hydrogen-containing chain extender in theaqueous phase.

[0062] Active hydrogen-containing chain extenders which may be reactedwith the isocyanate-terminated polyurethane prepolymer includeamino-alcohols, primary or secondary diamines or polyamines, hydrazine,and substituted hydrazines. Water itself may be effective as an indirectchain extender.

[0063] Where the chain extender is other than water, for example apolyamine or hydrazine, it may be added to the aqueous dispersion of theisocyanate-terminated polyurethane prepolymer or, alternatively, it mayalready be present in the aqueous medium when the isocyanate-terminatedpolyurethane prepolymer is dispersed therein.

[0064] Surfactants and or high shear can be utilised in order to assistin the dispersion of the polyurethane polymer(s) in water. Suitablesurfactants include but are not limited to conventional anionic,cationic and/or non-ionic surfactants such as Na, K and NH₄ salts ofdialkylsulphosuccinates, sulphated oils, alkyl sulphonic acids, alkylsulphates, fatty acids such as Na stearate and Na oleate. Other anionicsurfactants include alkyl or (alkyl)aryl groups linked to sulphonic acidgroups, phosphonic acid groups, or carboxylic acid groups. Cationicsurfactants include alkyl or (alkyl)aryl groups linked to quaternaryammonium salt groups. Non-ionic surfactants include polyglycol ethercompounds and polyethylene oxide compounds.

[0065] Component (B)(iii) may be any type of ultraviolet curable (UV)polymer(s) including for example polyether, polyurethanes, and vinylpolymers as are well known in the art. The UV curability results fromthe presence of olefinically unsaturated bonds and takes place by afree-radical mechanism. Olefinic unsaturation in a polymer may beobtained from the use of ethylenically unsaturated epoxides, for exampleepoxide (meth)acrylate; (methyl)acrylol groups; imines and ethylenicallyunsaturated epoxides or imines and ethylenically unsaturatedisocyanates, as described for example in WO 95/00560. Preferablycomponent (B)(iii) is based on polyurethanes or polyesters havingunsaturated moieties and on multifunctional acrylic polymers.

[0066] The radiation used for curing the UV curable polymer may be anysuitable form of radiant energy but is preferably UV radiation. Inprinciple electron-beam, gamma radiation, x-rays or visible radiationcould be used. When curing is effected by UV radiation, the compositionof the invention will normally include at least one photoinitiator,usually present in an amount 0.1 to 10 wt. % based on the weight of theUV curable polymer.

[0067] Examples of UV photoinitiators include halogenated polynuclearketones such as chlorosulphonated benzanthones, chlorosulphonatedfluorenones, alpha-haloalkylated benzanthones, alpha-haloalkylatedfluorenones and alkyl phenones. Accelerator compounds may be included ifdesired to enhance the cure rate.

[0068] Component (B)(iv) may be any autoxidisably crosslinkablepolymer(s). Autoxidisably crosslinkable polymers are polymers whichcrosslink on exposure to oxygen. The unsaturation present inautoxidisable polymers imparts latent crosslinkability so that when acoating composition thereof is dried in air (often in conjunction with adrier salt) the composition undergoes crosslinking, thereby improvingits properties such as mechanical properties (improved hardness anddurability) and chemical resistance.

[0069] Autoxidisably crosslinkable polymers are well known in the artand include alkyds; oils; fatty acid functionalised urethanes (alsoknown as uralkyds); unsaturated polyesters; and polymers with latentautoxidative functionality. Polymers bearing acetoacetoxy groups mayalso undergo autoxidative crosslinking after reaction with aminefunctional compounds. A further advantage of coatings containingunsaturated fatty acid residues is an improved glossy appearance. EP379007, EP 0017199 and EP 647644 all describe a one component emulsionwhich contain autoxidisable polymers with carboxylic acid groups toprovide water dispersibility.

[0070] Autoxidisably crosslinkable polyurethane polymers containingunsaturated fatty acid residues are preferably obtained from thereaction of at least one polyisocyanate with at least oneisocyanate-reactive compound bearing unsaturated fatty acid residue(s),optionally (but preferably) with isocyanate-reactive compounds bearingwater-dispersing groups and optionally isocyanate-reactive compoundsbearing neither unsaturated fatty acid residue(s) nor water-dispersinggroups.

[0071] The autoxidisably crosslinkable polyurethanes polymer may beprepared in a conventional manner by reacting the organicpolyisocyanate(s) with the isocyanate-reactive compound(s) by methodswell known in the prior art and as described above for component (B)(ii).

[0072] Preferred isocyanate-reactive compounds bearing unsaturated fattyacid residue(s) which may be used in the urethane synthesis may beobtained from the reaction, using techniques known in the art, of asuitable fatty acid with a hydroxyl donor (preferably an alcohol orpolyol) or amine donor to provide a fatty acid residue-bearing compoundwith at least one (preferably at least two) hydroxyl or amineisocyanate-reactive groups.

[0073] Preferred fatty acids include fatty acids derived from castoroil, soybean oil, sunflower oil, tallow oil, linseed oil and fatty acidssuch as linoleic acid, palmitoleic acid, linolenic acid, oleic acid,oleosteric acid, licanic acid, arachidonic acid, ricinoleic acid and/ormixtures thereof.

[0074] In the aqueous composition of the present invention component (A)and/or component (B) may also utilise further crosslinking mechanismsknown in the art.

[0075] Examples include but are not limited to Schiff base crosslinkingand silane condensation. By Schiff base crosslinking is meant thatcrosslinking takes place by the reaction of carbonyl functional group(s)such as an aldehyde, ketone or acetoacetyl group with acarbonyl-reactive amine or hydrazine (or blocked amine or hydrazine)functional group. By silane condensation is meant the reaction of alkoxysilane or —SiOH groups in the presence of water, to give siloxane bondsby the elimination of water and/or alkanols during the drying of theaqueous composition. Further examples include two component isocyanatecrosslinking and acid groups crosslinking with epoxy, carbodiimide,aziridine and/or oxazoline groups.

[0076] Preferably components (A) and (B) are prepared separately and aresubsequently blended together to prepare the aqueous composition of theinvention.

[0077] The aqueous composition of the invention preferably has a solidcontents of from about 20 to 60% by weight, more preferably from about25 to 45% by weight.

[0078] A co-solvent, as is well known in the coating art, is an organicsolvent employed in an aqueous composition to improve the dryingcharacteristics thereof. The co-solvent may be solvent incorporated orused during preparation of components (A) and/or (B) or may have beenadded during formulation of the aqueous composition.

[0079] Preferably the aqueous composition of the invention comprises 0to 15 wt. % of co-solvent, more preferably 0 to 10 wt. %, mostpreferably 0 to 5 wt. % and especially 0 to 1 wt. % of co-solvent byweight of components (A) and (B). Preferably the aqueous composition ofthe invention comprises no co-solvent added during the formulation ofthe aqueous composition.

[0080] Drier salts preferably comprise part of the composition ifcomponent (B) is autoxidisably crosslinkable ie. Component (B)(iv).Examples include polyvalent salts containing cobalt, calcium, copper,zinc, iron, zirconium and manganese as the cation and halides, nitrates,sulphates, acetates, napthenates or acetoacetonates as the anion. Theamount of drier used is usually in the range from 0 to 1% metal contentby weight of component (B)(iv).

[0081] The aqueous composition of the invention may contain otherconventional ingredients including organic solvents, pigments, dyes,emulsifiers, surfactants, thickeners, heat stabilisers, levellingagents, anti-cratering agents, fillers, sedimentation inhibitors, UVabsorbers, antioxidants, waxes and the like introduced at any stage ofthe production process or subsequently. It is possible to include anamount of an antimony oxide in the composition to enhance the fireretardant properties.

[0082] The aqueous composition of the invention may be advantageouslyemployed as coating compositions (e.g. protective or adhesive coatingcompositions) or inks, for which purpose they may be further dilutedwith water and/or organic solvents, or they may be supplied in moreconcentrated form by evaporation of water and/or organic of the liquidmedium. As coating compositions, they may be applied to any substrateincluding wood, metals, glass, cloth, leather, paper, plastics, foam andthe like, by any conventional method including brushing, dipping, flowcoating, spraying, and the like. According to the present inventionthere is also provided the use of the aqueous composition of theinvention as a coating composition.

[0083] The aqueous composition of the invention may also be used asadhesives for materials such as polypropylene, polyester, polyurethane,leather and the like or as binding agents for various particulatematerials.

[0084] According to the present invention there is provided a coatingobtained from an aqueous composition of the present invention.

[0085] In another embodiment of the present invention there is providedan adhesive obtained from an aqueous composition of the presentinvention.

[0086] There is still further provided according to the invention asubstrate coated with the aqueous composition of the present invention.

[0087] FIGS. 1 and 2 illustrate processes for preparing vinyl polymershaving a gradient polymeric morphology.

[0088]FIG. 1 is a block diagram illustrating the process for preparing avinyl polymer having a gradient polymeric morphology where a firstmonomer feed (1) is introduced into a reactor (3) with a stirrer (4) andsimultaneously a second monomer feed (2) is added to the first monomerfeed (1).

[0089]FIG. 2 is a block diagram illustrating the process for preparing avinyl polymer having a gradient polymeric morphology where a firstmonomer feed (1) and a second monomer feed (2) are introducedsimultaneously at different rates (a) and (b) into a reactor (3)equipped with a stirrer (4).

[0090] The present invention is now illustrated by reference to thefollowing examples.

[0091] Unless otherwise specified, all parts, percentages and ratios areon a weight basis. Examples denoted with a “C” are comparative examples.

Preparation of Vinyl Polymers having a Gradient Polymeric Morphology(VPG)

[0092] Vinyl Polymer having a Gradient Polymeric Morphology (VPG1)

[0093] A round-bottomed flask equipped with a condenser, thermometer andmechanical stirrer (the reactor) was charged with 490.8 parts of waterand 5.2 parts of sodium lauryl sulphate. At room temperature 5 parts ofa first monomer feed consisting of 153.6 parts of water, 118.3 parts ofmethyl methacrylate (MMA), 193.4 parts of butyl acrylate (BA), 77.9parts of butyl methacrylate (BMA) and 23.4 parts of sodium laurylsulphate was added to the reactor. Then 30% of a catalyst feedconsisting of 3.9 parts of ammonium persulphate (AP) and 255.9 parts ofwater was added to the reactor and the mixture was heated to 85° C.

[0094] As soon as the temperature reached 85° C. the second monomer feedaddition, consisting of 153.6 parts of water, 202.4 parts of methylmethacrylate, 78.1 parts of butyl acrylate, 77.9 parts of butylmethacrylate, 31.2 parts of methacrylic acid (MAA), and 23.4 parts ofsodium lauryl sulphate into the first monomer feed vessel was startedand addition from the first monomer feed vessel into the reactor wasstarted simultaneously. The feed rate from the second monomer feedvessel into the first monomer feed vessel and the feed rate from thefirst monomer feed vessel into the reactor were the same. The entiremonomer addition took 90 minutes. Together with the monomer addition theremainder of the catalyst feed was added and this took 100 minutes. Atthe end of the addition of the catalyst feed 100.0 parts of water wereused to rinse the feed tank and were added to the reactor. A temperatureof 85° C. was maintained for 30 minutes after which 1.4 parts of a 30w/w % solution of t-butyl hydroperoxide (tBHPO) in water and 8.4 partsof a 5 w/w % solution of iso-ascorbic acid were added to initiatepolymerisation of any remaining free monomer. The temperature was keptat 85° C. for another 30 minutes after which the emulsion was cooled toroom temperature.

[0095] At room temperature the emulsion was neutralised to a pH of 7using a 25% solution of ammonia in water and 0.9 parts of Proxel BD wasadded to prevent bacterial contamination of the emulsion.

[0096] The resulting emulsion had a solids content of 39.5%, a pH of7.0, a viscosity of 12 mPa.s, and an average particle size of 104 nm.

[0097] Vinyl polymer 2 (VPG2), Vinyl polymer 3 (VPG3) and Vinyl polymer4 (VPG4) were prepared using the same procedure described above for thepreparation of VPG1 using the components listed in Table 1 below. TABLE1 Components (g) VPG2 VPG3 VPG4 First Monomer Feed Water 153.6 153.6153.6 Methyl methacrylate 75.5 245.3 202.4 Butyl acrylate 205.1 66.578.1 Butyl methacrylate 77.9 77.9 77.9 Methacrylic acid 31.2 — 31.2Sodium lauryl sulphate 23.4 23.4 23.4 Second Monomer Feed Water 153.6153.6 153.6 Methyl methacrylate 245.3 75.5 118.3 Butyl acrylate 66.5205.1 193.4 Butyl methacrylate 77.9 77.9 77.9 Methacrylic acid — 31.2 —Sodium lauryl sulphate 23.4 23.4 23.4 Emulsion properties Solids content(%) 39.1 39.9 39.7 PH 6.7 7.0 6.8 Viscosity (mPa · s) 12 8 12 Averageparticle size (nm) 98 140 124

Further Preparation of Vinyl Polymers having a Gradient PolymericMorphology VPG6 to VPG14

[0098] A round-bottomed flask equipped with a condenser, thermometer andmechanical stirrer was charged with 552.0 parts of water and 4.5 partsof Aerosol GPG, (sodium dioctyl sulphosuccinate surfactant availablefrom American Cyanamid). The reactor contents were heated to 50° C. atwhich temperature a certain percentage (as listed below in Table 2) ofthe first monomer feed was added to the reactor. The amounts andmonomers used for the first and second monomer feeds are listed in Table2. The reaction mixture was further heated to 70° C. at which point 30%of the initiator feed was added. The total initiator feed comprised 83.3g of a 3% AP solution. The mixture was then further heated to 85° C. atwhich point the feeding of the second monomer feed into the firstmonomer feed and simultaneously feeding of the first monomer feed intothe reactor started. At the same time the initiator feed was started.The entire monomer initiator addition took 120 minutes. The reactor waskept at 85° C. for another 30 minutes followed by a post-reaction using1.4 of a 30% tBHPO solution together with 8.3 gram of a 5% iso-ascorbicacid solution followed by another 30 minutes holding period. Finally,the pH was adjusted to around 8 using 12.5% ammonia. TABLE 2 Component(g) VPG5 VPG6 VPG7 VPG8 VPG9 VPG10 VPG11 VPG12 VPG13 VPG14 First monomerfeed Water 71.4 107.1 142.9 107.1 142.9 142.9 107.1 107.1 105.6 35.2Aerosol 2.7 4.0 5.4 4.0 5.4 5.4 4.0 4.0 4.0 1.3 GPG MMA 131.3 215.4287.2 215.4 262.6 287.2 197.0 215.4 240.7 80.4 BMA 18.7 22.1 29.5 22.137.4 29.5 28.0 22.1 — — MAA 8.3 12.5 16.7 12.5 16.7 16.7 12.5 12.5 5.71.9 MAAM 8.3 — — — 16.7 — 12.5 — — — Amount of 0% 5% 10% 0% 5% 0% 10% 5%5% 5% seed Second monomer feed Water 285.7 250.0 214.3 250.0 214.3 214.3250.0 250.0 246.4 316.8 Aerosol 1.4 1.4 1.4 9.4 8.0 8.0 9.4 9.4 9.2 11.9GPG MMA 223.6 195.6 137.5 207.1 207.7 244.9 285.7 242.3 186.6 239.8 BA443.1 — — 347.1 292.3 255.1 297.6 341.0 106.6 137.0 MAAM — — 25.0 29.2 —— — — — BMA — — — — — — — — 213.2 274.1 2-EHA — — — — — — — — 26.7 34.3MAA — — — — — — — — 13.2 17.0 DAAM — — — — — — — — 28.7 37.0 Emulsionproperties Solids (%) 42.5 42.5 42.5 42.5 42.5 42.5 42.5 42.5 42.5 42.5Viscosity 24 43 39 32 32 35 37 40 32 40 (mPa · s) pH 8.1 8.3 7.9 8.0 8.28.4 8.3 8.3 8.6 8.4

Preparation of Sequential Vinyl Polymers (SVP)

[0099] Sequential Vinyl Polymer (SVP15)

[0100] A round-bottomed flask equipped with a condenser, thermometer andmechanical stirrer (reactor) was charged with 490.8 parts of water and5.2 parts of sodium lauryl sulphate. At room temperature 5% of a firstmonomer feed consisting of 153.6 parts of water, 118.3 parts of methylmethacrylate, 193.4 parts of butyl acrylate, 77.9 parts of butylmethacrylate and 23.4 parts of sodium lauryl sulphate was added. Then30% of a catalyst feed consisting of 3.9 parts of ammonium persulphateand 255.9 parts of water was added and the mixture was heated to 85° C.

[0101] As soon as the temperature reached 85° C. feeding of the firstmonomer feed and of 50% of the remaining catalyst feed into the reactorwere started. The first monomer feed was added over a period of 45minutes, while the catalyst feed took 55 minutes. After completeaddition of the first monomer feed the temperature was kept at 85° C.for 30 minutes to ensure complete polymerisation of monomers. Next theaddition of a second monomer feed consisting of 153.6 parts of water,202.4 parts of methyl methacrylate, 78.1 parts of butyl acrylate, 77.9parts of butyl methacrylate, 31.2 parts of methacrylic acid, and 23.4parts of sodium lauryl sulphate and the remaining catalyst feed werestarted. The second monomer feed took 45 minutes, while the remainingcatalyst was fed in 55 minutes. At the end of the addition of thecatalyst feed 100.0 parts of water were used to rinse the feed tank andwere added to the reactor. A temperature of 85° C. was maintained for 30minutes after which 1.4 parts of a 30 w/w% solution of t-butylhydroperoxide in water and 8.4 parts of a 5 w/w% solution ofiso-ascorbic acid were added to initiate polymerisation of any remainingfree monomer. The temperature was kept at 85° C. for another 30 minutesafter which the emulsion was cooled to room temperature.

[0102] At room temperature the emulsion was neutralised to a pH ofaround 7 using a 25% solution of ammonia in water and 0.9 parts ofProxel BD was added to prevent bacterial contamination of the emulsion.

[0103] The resulting emulsion had a solids content of 39.6%, a pH of6.6, a viscosity of 11 mPa.s, and an average particle size of 115 nm.

[0104] Sequential vinyl polymer 16 (SVP16), sequential vinyl polymer 17(SVP17) and sequential vinyl polymer 18 (SVP18) were prepared using thesame procedure described above for the preparation of SVP15 using thecomponents listed in Table 3 below. TABLE 3 Components (g) SVP16 SVP17SVP18 First Monomer Feed Water 153.6 153.6 153.6 Methyl methacrylate75.5 245.3 202.4 Butyl acrylate 205.1 66.5 78.1 Butyl methacrylate 77.977.9 77.9 Methacrylic acid 31.2 — 31.2 Sodium lauryl sulphate 23.4 23.423.4 Second Monomer Feed Water 153.6 153.6 153.6 Methyl methacrylate245.3 75.5 118.3 Butyl acrylate 66.5 205.1 193.4 Butyl methacrylate 77.977.9 77.9 Methacrylic acid — 31.2 — Sodium lauryl sulphate 23.4 23.423.4 Emulsion properties Solids content (%) 40.2 39.3 40.0 pH 7.0 6.97.0 Viscosity (mPa · s) 17 10 14 Average particle size (nm) 105 127 124

Vinyl Polymer Containing Particles with a High Tg and a Small ParticleSize (VP19)

[0105] A round-bottomed flask equipped with a condenser, thermometer andmechanical stirrer was charged with 1288.6 parts of water, 44.3 parts ofsodium lauryl sulphate and 2.9 parts of ammonium persulphate. Thismixture was heated to 50° C. At 50 C 5% of a monomer feed consisting of548.3 parts of methyl methacrylate and 28.8 parts of 2-hydroxyethylmethacrylate was added and the mixture was further heated to 85° C. Assoon as the reaction temperature was reached the remaining monomer feedwas added over a period of 60 minutes. At the end of the addition of themonomer feed 15.2 parts of water were used to rinse the feed tank andwere added to the reactor. A temperature of 85° C. was maintained for 60minutes after which the emulsion was cooled to room temperature. At roomtemperature the emulsion was neutralised to a pH of 7.4 using a 25%solution of ammonia in water and 2.0 parts of Proxel BD mixed with 11.4parts of water were added to prevent bacterial contamination of theemulsion.

[0106] The resulting emulsion had a solids content of 29.7%, a pH of7.4, a viscosity of 14 mpa.s, a calculated Tg of 101° C. and an averageparticle size of 54 nm.

[0107] Urethane Polymer, Self-dispersible, Carboxylic Acid Stabilised(UP20)

[0108] A round-bottomed flask equipped with a thermometer and mechanicalstirrer was charged with 304.7 parts of isophorone diisocyanate, 40.0parts of dimethylol propionic acid (DMPA), 455.3 parts of polypropyleneglycol mixture (Voranol; OH value=76.6 mg KOH/g; Dow Benelux, TheNetherlands) and 0.15 parts of tin octoate and the reaction mixture wasslowly heated to 95° C. under a dry air atmosphere. The reaction mixturewas held at this temperature until the NCO content was 7.59%.Subsequently 24.79 parts of triethylamine were added to the reactionmixture. 650 parts of the reaction mixture was dispersed into a mixtureof 1040 parts of water containing 16 parts of a nonyl phenol ethoxylate(Igepal C0 -630; Rhodia, Belgium) during 1 hour to form an aqueousdispersion of the NCO-terminated prepolymer. Thereafter 26.5 parts ofhydrazine were added as a 64.5% solution in water to chain-extend theNCO-terminated prepolymer.

[0109] The resulting translucent polyurethane dispersion had a solidscontent of 38.6% and a pH of 7.3.

[0110] UV-curable Carboxylic Acid Stabilised Polyurethane Polymer(UV-UP21)

[0111] A round-bottomed flask equipped with a thermometer and mechanicalstirrer was charged with 330.7 parts of isophorone diisocyanate, 37.5parts of dimethylol propionic acid (DMPA), 52.5 parts of an acryloylfunctional polyol CN104 (OH number=233.9 mg KOH/g; Cray Valley, France),329.3 parts of a polyester diol S-1063-120 (OH number=120 mg KOH/g;Occidental Chemical, Belgium), 0.15 parts of2,6-di-tert-butyl-4-methylphenol (lonol CP) and 0.15 parts of tinoctoate and the reaction mixture was slowly heated to 95° C. under a dryair atmosphere. The reaction mixture was held at this temperature untilthe NCO content was 8.04%. Subsequently 28.3 parts of triethylamine wereadded to the reaction mixture. 500 parts of the reaction mixture wasdispersed into 905 parts of water during 1 hour to form an aqueousdispersion of the NCO-terminated prepolymer. Thereafter 22.9 parts ofhydrazine were added as a 64.5% solution in water to chain-extend theNCO-terminated prepolymer.

[0112] The resulting translucent polyurethane dispersion had a solidscontent of 34.6% and a pH of 8.0. The unsaturated bond functionality was0.57 mmoles C═C/g polymer.

[0113] Autoxidisable Polymer (AP22)

[0114] Dynotal LS82, available from Dyno ASA, Norway was used for AP22with an oil length of 82% wherein the fatty acids consisted of soybeanoil fatty acid and linseed oil fatty acid.

Vinyl Polymer Containing Particles with a High Tg and a Small ParticleSize (VP23)

[0115] NeoCryl XK-25, available from NeoResins, Avecia BV was used assupplied. NeoCryl is a trademark of Avecia BV.

[0116] NeoCryl XK-25 has a measured Tg>80° C. and a particle size<50nm.

[0117] Autoxidisable Polymer AP24

[0118] Bayhydrol B130, a water reducible, oxidatively dryingstyrene-butadiene resin, available from Bayer was used for AP24.Bayhydrol is a trademark of Bayer.

[0119] Urethane Polymer 25 (UP25)

[0120] Bayhydrol VP LS2342, a polyurethane dispersion available fromBayer was used for UP25.

[0121] Alkyd Polymer 26 (AP26)

[0122] Uradil az 554z-50, an alkyd dispersion available from DSM Resinswas used for AP 26. Uradil is a trademark of DSM Resins.

[0123] UVF-curable Vinyl Polymer 27 (UV-VP27)

[0124] Lux 352, a UV curable aqueous acrylic dispersion, available fromAlberdingk Boley was used for UV-VP27. Lux is a tradename of AlberdingkBoley.

[0125] Analytical Methods

[0126] Surface Hardness

[0127] König hardness was determined following DIN 53157 NEN 5319 usingan Erichsen hardness equipment. The values are given in seconds (s).

[0128] MFFT

[0129] The minimum film formation temperature (°C.) was determined usingDIN 53787 using a Sheen MFFT bar SS3000.

[0130] Particle Size

[0131] Average particle sizes were determined using a Malvern Zetasizer3000HSa.

[0132] Elasticity and Toughness

[0133] On a 200×300 mm glass plate 400 μm films were applied using abird blade applicator (model 288). The films were dried for 16 hours atambient temperature followed by ageing of the film for 16 hours at 50°C. The glass plates were submersed in water to release the clear filmswhich were subsequently dried at 50° C. during 16 hours. From each film5 standard tensile test specimens were produced using a DIN 52-910-53puncher. A Instron tensile test instrument was used. The elasticity andtoughness were determined at a crosshead speed of 100 mm/min, and asample rate of 20.00 pts/sec and are the mean value of 5 test specimens.The thickness of the test specimens varied between 80-100 μm. Thedetermination was carried out at 20° C. and a relative humidity of 60%.

EXAMPLES

[0134] Examples 1 to 4, 9 and 10 of the present invention comprisingblends of the vinyl polymers having a gradient polymeric morphology(VPG1-4) with VP19 (vinyl polymer small particle size, high Tg) andcomparative examples 5 to 8, 11 and 12 comprising blends of thesequential vinyl polymers (SVP15-18) with VP19 were made in w/w % blendratios of 90:10 and 70:30 as shown below in Table 4. Examples 1 to 4, 9and 10 show an improved balance of physical properties. TABLE 4 VPGsurface tough- elas- VPG or % or VP9 MFFT hard- ness ticity SVP SVP % %(° C.) ness (s) (MPa) (%) EX. 1 VPG1 90 10 33 62 2.0 147 EX. 2 VPG2 9010 30 69 10.6 100 EX. 3 VPG3 90 10 30 69 12.7 93 EX. 4 VPG4 90 10 31 551.8 142 CEX. 5 SVP15 90 10 62 71 1.1 13 CEX. 6 SVP16 90 10 30 45 1.5 107CEX. 7 SVP17 90 10 27 52 0.8 80 CEX. 8 SVP18 90 10 34 49 0.7 54 EX. 9VPG1 70 30 26 92 — — EX. 10 VPG2 70 30 28 74 — — CEX. 11 SVP15 70 30 6080 — — CEX. 12 SVP16 70 30 27 60 — —

[0135] Examples 13, 14 and 17 to 19 of the present invention comprisingblends of the vinyl polymers having a gradient polymeric morphology(VPG1-4) with UP20 (urethane polymer) and comparative examples 15, 16and 20 and 21 comprising blends of the sequential vinyl polymers (SVP16and 18) with UP20 were made in w/w % blend ratios of 90:10 and 70:30 asshown below in Table 5. Examples of the invention in Table 5 show animprovement in surface hardness. TABLE 5 VPG or VPG % or surface SVP SVP% UP20 %. MFFT (° C.) hardness (s) EX. 13 VPG2 90 10 <5 62 EX. 14 VPG390 10 <5 64 CEX. 15 SVP16 90 10 <5 53 CEX. 16 SVP17 90 10 <5 52 EX. 17VPG2 70 30 <5 52 EX. 18 VPG3 70 30 <5 55 EX. 19 VPG4 70 30 <5 56 CEX. 20SVP16 70 30 <5 43 CEX. 21 SVP17 70 30 <5 38

[0136] Examples 22 to 24 and 28 to 30 of the present inventioncomprising blends of the vinyl polymers having a gradient polymericmorphology (VPG1-4) with UV-UP21 (UV curable polymer) and comparativeexamples 25 to 27 and 31 to 33 comprising blends of the sequential vinylpolymers (SVP15-18) with UV-UP21 were made in w/w % blend ratios of90:10 and 70:30 as shown below in Table 6. Examples of the inventionshown in Table 6 show an improvement in surface hardness. TABLE 6 VPG orVPG % or MFFT surface SVP SVP % UV-UP21 % (° C.) hardness (s) EX. 22VPG2 90 10 <5 105 EX. 23 VPG3 90 10 <5 98 EX. 24 VPG4 90 10 <5 95 CEX.25 SVP16 90 10 <5 71 CEX. 26 SVP17 90 10 <5 70 CEX. 27 SVP18 90 10 <5 85EX. 28 VPG1 70 30 <5 116 EX. 29 VPG2 70 30 <5 118 EX. 30 VPG3 70 30 <5112 CEX. 31 SVP15 70 30 <5 105 CEX. 32 SVP16 70 30 <5 87 CEX. 33 SVP1770 30 <5 87

[0137] Examples 34, 35, 38 and 39 of the present invention comprisingblends of the vinyl polymers having a gradient polymeric morphology(VPG1-4) with AP22 (autoxidisable polymer) and comparative examples 36,37, 40 and 41 comprising blends of the sequential vinyl polymers(SVP15-18) with AP22 were made in w/w % blend ratios of 90:10 and 70:30as shown below in Table 7. Examples of the invention shown in Table 7show an improvement in the MFFT/surface hardness balance. TABLE 7 VPG orVPG % or Surface SVP SVP % AP22 % MFFT (° C.) hardness (s) EX. 34 VPG190 10 43 77 EX. 35 VPG2 90 10 43 61 CEX. 36 SVP15 90 10 67 24 CEX. 37SVP16 90 10 69 39 EX. 38 VPG1 70 30 41 31 EX. 39 VPG2 70 30 39 23 CEX.40 SVP15 70 30 71 24 CEX. 41 SVP16 70 30 66 34

[0138] Examples 42 to 47 of the present invention comprising blends ofvinyl polymers having a gradient polymeric morphology (VPG7 to VPG12)with VP23 (vinyl polymer, small particle size, high Tg) were made in w/w% blend ratios of 90:10 as shown in Table 8 below.

[0139] Table 8 shows that the blends of various vinyl polymers having agradient polymeric morphology with VP23 give a favourable MFFT/surfacehardness balance combined with high elasticity and toughness. TABLE 8Elas- Tough- VPG VP23 MFFT Surface ticity ness VPG % % (° C.) hardness(s) (%) (MPa) Ex. 42 VPG 7 90 10 31 102 97 9.5 Ex. 43 VPG 8 90 10 30 89159 14.0 Ex. 44 VPG 9 90 10 43 84 158 11.9 Ex. 45 VPG10 90 10 47 56 13113.7 Ex. 46 VPG11 90 10 21 71 153 12.2 Ex. 47 VPG12 90 10 27 79 207 10.2

[0140] Examples 48 to 53 of the present invention comprising blends ofvinyl polymers having a gradient polymeric morphology (VPG5, VPG6, VPG12and VPG13) were blended in w/w % ratios as shown in Table 9 below withAP24, UP25, AP26 and UV-VP27.

[0141] The blend with UV-VP27 (Ex.49) was formulated with 0.18 gram ofDarocure 1173 a photoinitiator available from Ciba Specialty Chemicals.The film was allowed to dry at room temperature until touch dry before aflash-off at 60° C. for 10 minutes followed by UV curing at 400 mJ (twotimes).

[0142] The blend with UP25 (Ex.50) was formulated with 10%ethylenediglycol (EDG).

[0143] The blend with AP24 (Ex.48) was formulated with 0.06 wt. % Co onAP24 solids as per recommendation by Bayer.

[0144] The blend with AP26 (Ex. 53) was formulated with 5% EDG.

[0145] Table 9 shows that up to 40 wt. % of component (B) gives coatingswith a high elasticity, toughness and good MFFT surface hardnessbalance. TABLE 9 AP, UP AP, UP Surface or VPG or MFFT hardness ToughnessVPG UV-VP % UV-UP % (° C.) (s) Elasticity % (MPa) Ex. 48 VPG5 AP24 80 20<5 29 187 10.2 Ex. 49 VPG6 UV-VP27 90 10 <5 48 138 8.0 Ex. 50 VPG13 UP2590 10 40 79 78 12.3 Ex. 51 VPG5 UP25 70 30 <5 30 251 13.0 Ex. 52 VPG5UP25 60 40 <5 34 258 14.5 Ex. 53 VPG12 AP26 85 15 20 59 206 13.0

[0146] Comparative Examples 54 to 59 comprise blends of vinyl polymershaving a gradient polymeric morphology (VPG7, VPG13 and VPG14) with morethan 50 wt. % of VP23, UP25, AP24 and AP26, as shown in Table 10 below.The blends with VP23 (CEX.54 and CEX.55) were formulated with 20% EDG.Table 10 shows that having less than 50 wt. % of component (A) resultsin a very high MFFT and low elasticity, coatings that are too brittle orcoatings with low hardness and toughness. TABLE 10 Surface VP, UP VP, UPMFFT hardness Elasticity Toughness VPG or AP VPG % or AP % (° C.) (s)(%) (MPa) CEX. 54 VPG 7 VP23 40 60 69 120 66 12.7 CEX. 55 VPG 7 VP23 2080 <90 107 47 10.7 CEX. 56 VPG 13 UP25 30 70 <5 94 Too brittle Toobrittle CEX. 57 VPG13 UP25 35 65 <5 90 Too brittle Too brittle CEX. 58VPG13 AP24 35 65 <5 115 Too brittle Too brittle CEX. 59 VPG14 AP26 40 6011 17 119 1.6

1: An aqueous composition comprising in admixture components: (A) 70 to90 wt. % of a vinyl polymer(s) having a gradient polymeric morphology;and (B) 10 to 30 wt. % of at least one polymer not having a gradientpolymeric morphology; wherein component (A) is blended with component(B) and components (A) and (B) add up to 100%. 2: An aqueous compositionaccording to claim 1 wherein component (A) is obtained by thepolymerisation of at least a first monomer feed and a different secondmonomer feed. 3: An aqueous composition according to claim 2 whereincomponent (A) is obtainable from a process comprising introducing afirst monomer feed to a reactor, where the first monomer feedcontinually varies in its composition due to the addition of a differentsecond monomer feed to the first monomer feed and polymerising themonomers introduced into the reactor. 4: An aqueous compositionaccording to claim 2 wherein component (A) is obtainable from a processcomprising simultaneously introducing a first monomer feed and adifferent second monomer feed into a reactor where the rate ofintroduction of the first monomer feed varies with respect to the rateof introduction of the second monomer feed and polymerising the monomersintroduced into the reactor. 5: An aqueous composition according toclaim 2 where the weight ratio of the first monomer feed to thedifferent second monomer feed is in the range of from 70:30 to 30:70. 6:An aqueous composition according to claim 2 where either the firstmonomer feed and/or the second monomer feed comprises composition (a):i) 10 to 90 wt. % of CH₂═R¹ COOR² where R¹ is H or methyl and R² isoptionally substituted alkyl or cycloalkyl of 4 to 20 carbons atoms; ii)0 to 40 wt. % of styrene; iii) 0 to 15 wt. % of acid functional vinylmonomer(s); iv) 0 to 10 wt. % of crosslinking functional vinylmonomer(s); v) 0 to 5 wt. % of chain transfer agent(s) vi) 0 to 20 wt. %of vinyl monomer(s) not in i) to vi) where i)+ii)+iii)+iv)+v)+vi) add upto 100%; and wherein said second monomer feed is different from saidfirst monomer feed. 7: An aqueous composition according to claim 2 whereeither the first monomer feed and/or the second monomer feed comprisescomposition (b): i) 10 to 90 wt. % of CH₂═CR¹—COOR² where R¹ is H ormethyl and R² is optionally substituted alkyl or cycloalkyl of 1 to 20carbon atoms; ii) 0 to 40 wt. % of styrene; iii) 2 to 20 wt. % of acidfunctional monomer(s); iv) 0 to 30 wt. % of crosslinking functionalmonomer(s); v) 0 to 10 wt. % of chain transfer agent(s); vi) 0 to 20 wt.% of vinyl monomer(s) not in i) to vi); where i)+ii)+iii)+iv)+v)+vi) addup to 100%; and wherein said second monomer feed is different from saidfirst monomer feed. 8: An aqueous composition according to claim 1wherein component (A) is obtained from a seeded polymerisation process.9: An aqueous composition according to claim 1 where component (B) isselected from the group comprising: (i) vinyl polymer(s) having a Tg≧50°C. and a particle size≦150 nm; (ii) water-dissipatable polyurethane(s);(iii) UV curable polymer(s); and (iv) autoxidisably crosslinkablepolymer(s). 10: An aqueous composition according to claim 1 comprising 0to 15 wt. % of co-solvent by weight of components (A) and (B). 11: Useof an aqueous composition according to claim 1 as a coating composition.12: A coating obtained from an aqueous composition according to claim 1.13: An adhesive obtained from an aqueous composition according toclaim
 1. 14: A substrate coated with an aqueous composition according toclaim 1.